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Nature of Science

Nature of Science. Science T/F. Science is a system of beliefs. Scientists rely heavily on imagination to carry out their work. 3. Scientists are totally objective in their work. Science T/F. 4. The scientific method is the accepted guide for conducting research.

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Nature of Science

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  1. Nature of Science

  2. Science T/F • Science is a system of beliefs. • Scientists rely heavily on imagination to carry out their work. 3. Scientists are totally objective in their work

  3. Science T/F 4. The scientific method is the accepted guide for conducting research. 5. Experiments are carried out to prove cause-and-effect relationships.

  4. Science T/F 6. All scientific ideas are discovered and tested by controlled experiments. 7. A hypothesis is an educated guess. 8. Scientific ideas are tentative and can be modified or disproved.

  5. What is Science? • It uses previous knowledge and theories to gain new knowledge and to produce new and better theories through observations of the natural world.

  6. What is science? • Science is a process to build understanding. • Example: The earth was once believed to be flat. • Do we still think this today? Why?

  7. What science is NOT? • Is not a system of beliefs • Does not prove anything! It can only accept the best explanation at that time until it is disproved.

  8. What science is NOT? • Science cannot make decisions about morals, laws, literature, visual arts, music, etc. • It cannot draw conclusions about things it cannot measure or manipulate.

  9. Science as moral solution? • Can science offer a solution to whether stem cell research is right or wrong? • NO! It can offer only information gained from research and observations in order for people to make their decisions.

  10. Hypothesis, Laws, and Theories • Hypothesis: testable explanation based on previous observations • Law: general statement that describes a natural phenomena • Theory: explanation of how a law works

  11. Laws and Theories • Atomic Theory explains the Law of Conservation of Mass • Chromosomal theory of inheritance explains the Law of Heredity

  12. 14.1 Darwin Developed a Theory of Evolution

  13. I. Idea’s From Darwin’s Time A. Evolution is all of the changes that have transformed life over time • In the mid 1700’s George Buffon suggested that the Earth is older than 10,000 years old • In the early 1800’s Jean Baptiste Lamarck developed the idea of Inheritance of Acquired Characteristics

  14. II. The Voyage of the Beagle A. In 1831 The HMS Beagle left England for a five year voyage around the world B. Darwin studied the geology, plants, and animals he encountered

  15. III. Darwin’s Observations A. Darwin maintained extensive journals of his observations, studies and thoughts • Darwin noticed the animals and plants he observed were uniquely South American • Darwin was especially intrigued by the Galapagos Islands because of their diversity

  16. IV. Ideas from Geology A. Darwin read books from Charles Lyell that proposed Earth’s features today could be explained by geological processes B. From this Darwin made two conclusions 1. The Earth must be very old 2. Slow and gradual processes occurring over vast amounts of time could cause tremendous change

  17. V. Darwin Publishes His Theory A. Over many years after his return, Darwin developed his theory based on observations, inferences and ideas B. In 1844 Darwin wrote a 200 page essay that outlined his idea C. In 1859 Darwin released his findings to the public in the book TheOrigin of Species

  18. VI. Darwin’s Two Main Points A. Darwin’s first point was that the species of organisms living on Earth today descended from ancestral species, Descent with Modification B. Darwin’s second main point was that Natural Selection is the mechanism for evolution

  19. Natural Selection

  20. 14.2 Evolution has left much evidence

  21. I. The Fossil Record A. Preserved remains or markings left by organisms that lived in the past are called fossils B. The positions of fossils in the rock strata can reveal relative age C. The fossil record is this chronological collection of life’s remains in the rock layers

  22. Fossil Formation

  23. Fossil Evidence Basilosaurus

  24. II. Geographic Distribution A. The differences and similarities between organisms and different parts of the world shows how species today evolved from ancestral forms B. Geographic distribution gives clues as to how modern species evolved

  25. III. Similarities in Structure A. Similar structures in species sharing a common ancestor are called homologous structures B. Vestigial structures are remnants of structures that may have had important functions in an ancestral species, but have no clear function today

  26. Homologous Structure

  27. IV. Similarities in Development A. Embryos of closely related organisms often have similar stages in development B. Comparing the development of organisms supports other evidence of homologous structures

  28. Embryo Similarities

  29. V. Molecular Biology • The closer two organisms DNA sequence match, the closer the relationship • DNA and protein analysis are new tools for testing hypothesis about evolution C. There is molecular evidence that there are common genetic codes shared by all species

  30. Human DNA into Bacterial DNA

  31. GFP in Mice

  32. Similar Amino Acids

  33. 14.3 Darwin proposed natural selection as the mechanism of evolution

  34. I. Darwin’s Theory of Natural Selection A. A population is a group of individuals of the same species in the same area at the same time B. Populations in different areas become more and more different, leading to new species

  35. II. Observations Lead to A Question A. There are 13 species of finches unique to the Galápagos Islands B. They most closely resemble one finch species living on the South American mainland

  36. III. More Observations Lead to an Idea A. Darwin recognized that all species tend to produce excessive numbers of offspring B. Darwin also recognized there was variation among the individuals of a population

  37. Stabilizing Selection

  38. Directional Selection

  39. Disruptive Selection

  40. IV. Artificial Selection A. Artificial selection is the selective breeding of domesticated plants and animals to produce offspring with traits that humans value B. You see this change in Dog’s over the last 500 years

  41. Lion & Liger

  42. Tiger and Tigon

  43. Dog Breeding

  44. Labradoodle

  45. V. Pesticides-Natural Selection in Action A. When a new pesticide is sprayed it will kill about 99% of the insects targeted B. As time goes on, more insects are resistant to the pesticide

  46. Cockroaches

  47. Pesticides- natural selection C. This illustrates two key points about natural selection 1. natural selection is a “screening” of the traits available 2. natural selection favors those characteristics in a varying population that fit the specific current, local environment

  48. Pesticide Resistance

  49. Natural Selection

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